Method of making bifocal lenses



E. PAIGE. METHOD OF MAKING BIFOCAL LENSES. APPLICATION 'HLEU MAY 27. 19:5. 1,302,960. I Patented M36, 1919.:

" a swans-4km I.

lTNss gg; INVENTORH, I i 11111 A. E. PAIGE; METHOD OF MAKING BIFUCAL LENSES. I APPLICATION FILED 1111,1915 1 1,302,960. Patented May 6, 1919.

a SHEETS-SHEET 2.

"WI'I'NESSEii-T: INVENTOR:

A. E. PAIGE.

METHOD OF MAKING BIFOCAL LENSES.

APPLICATION mtu m n/21.19:

Patented May 6, 1918.

'8 SHEETS-SHEET 3- A. E. PAIGE, METHOD OF [MAKING bvrocm. Lznsgs,

APPLICATION FILED H27. 1915, I 1,302,960. Patented May 6,1918}.

TNEssEs. INVENTOR:

A. E. PAIGE.

METHOD OF MAKING BIFOCAL LENSES. APPLICATION FILED MAYZ]. 1915.

8 SHEETS-8HEET 5'.

ITNESSE Patented Mai 6, 191

A. E. PAIGE; METHOD (3f MAKI NG BIFOCAL LENSES.

APPLICATIUH FILED MAYZI. ISIS.

Patented Mayfi,1919.

A. E. PAIGE.

METHOD0F MAKING BIFOCAL LENSES. I APPucm'oN men MAY 21. 1915. 1,302,960, Patented May 6,1919,

8 SHEETS-SHEET 7 wiTNEgsmEsz I .jlNVENTOR:

A. EQ PAIGE. METHOD OF MAKING BIFOCM LENSES.

APPLICATION FILED MAY 21. 1s a 5.

P atented May 6, 1919;

a SHEEN-such 8.

IN ENTOR:

W11 I I I U I ED sTATEsPArENr clarion."

' anrrma 1:. runs, or rnrnnnnnrnrn, PENNSYLVANIA. 7

METHOD OF MAKING BIFOCAL LENSES.

, I l \n" Specification of Letters Patent.

Patented M 6, 1919.

ori' mar l iucatibima mien 4', 1915, Serial No. 12,o2s. Divided and this application filed m 27, 1915, I I Serial llo.,30,718. 1

To all toiiom it may concern: I

Be it known that .I, ARTHUR E.-PAIGE, a

citizen of the United States, residing at Philadelphia,"in the State of Pennsylvania, have invented a" certain new and useful Improvement in Methods of Making Bifocal Lenses,- whereof the following is a specification, reference being had to the accompanying draw m fi.

y invention relates to methods of producing curved surfaces, and particularly such surfaces which adjoin each otherand are respectively uniformly curved to the junctlon line between them, so as to sharply define the latter; A s hereinafter described, my method is adapted to surface one side of glass to contemporaneously form a pair of bifocal lenses, the glass being held with the respective minorareas adjoining each other and between their respe'ctive major areas and concentrically rotatedin' eoiiperativ'er elation with abrading means common to the glass which forms botlrmembers of such a pair. Such abradmg means may include a lap having' an annular abrading surfacepresenting only a transverse'line of contact to the glass and having one circumferential edge of said annular surface presentedtangentiallyto the junction line between the major and minor lens areas, so that that edge of the abrading surface extends obliquely over said Junction line from its point of contact I with the glass; whereby the glass 'is,abraded in a direction transverse to said junction line, ,so as to sharply, define the'latter. As hereinafter described such oblique relation may be determined by having the axes of rotatlon of the'glass andof the lap neither "parallel nor at right. angles, but in acutely 1 thus maintained in abrading the major lens surfaces; because the path of the abrading "material moved, by the lapis then in a directreferred to as a circletion transverse to the path of the abrading material moved by the glass, thus'impar ting a compound decussative motion to said material and preventing it from forming concentric. ruts or scratches in the glass. "Moreover, by presenting the line of contact of the.

lap with the glass in tangential relation to a. circle of rotation of the latter, a spherically curved surface of a given radius may be produced by a lap surface of less radius, which is advantageous in that such a. lap may be adjusted to and from radial and tangcntial position to compensate for wear of its abrading surface.

F or instance, a lap having a conoidal abrading surface which is circularly arcually curved respectively differently transversely and circumferentially, when presenting a transverse line of contact-to the glass in radial relation to the axis of rotation of the latter, produces a spherical surface of precisely the same radius as the transverse curvature of the lap surface, and, as the lap surface is rendered moreconvex by use, the line ofcontact may be shifted to tangential relation to a circle of rotation of the glass to produce a spheri cal surface of the givenradius with the lap surface then of a less radius. Of course,

such adjustment to and from radial and tangential position is limited to the extent of the radius of the circular perimeter of the minor lens areas.

My invention includes the various novel features of procedure hereinafter more defi nitely specified.

This is a division of my application Serial N01 12,028 filed March 4, 1915,, pursuant to which Letters Patent of the United States 1,269,568 were, granted to me J une 11, 1918. Letters Patent of the United States 1,260,022 were also granted to me March 19, 1918, pillsuant to application Serial No. 178,523, filed July 4,1917, as another division ofsaid upp'l'ication Serial No. 12,028, and, in both of said Letters Patent mechanism of the character herein described is claimed. 1

Figure I is a fragmentary plan view of a surfacing machine, including a lever having a universal fulcrum, by which lap elements of my invention may be adj ustably support-- ed; one of said lap elements being indicated" in dash lines in position to present a transverse line of contact of its annular abrading surface, to the major lens surface of the glass which is to be abraded, and tangential relation to'a circle of rotat1on de- "scribed by any point on the surface of said glass.

6 Fig. II is an elevation of the universal fulcrum sup rt for thelevcr shown in Fig. I.

is precisely limited. 10 lg. IV is a diagrammatic 'lan view indicating, in dash lines, a lap laving its annular abrading surface presenting a transverse line of contact to said glass, at the minorlens areas of the latter and in' radial relationwith the axis of rotation of the glass. '1 1 Fig. a diagrammatic plan view, whereinth gdap illustrated in Fig. 1, indicated iii-gash lines, is shifted to present its line of-co tact ,to the'glass'at the maqor lens surface pf the latter and in radial relation with the axis of rotation of the glass.

' Fig. VI isa plan view of "a rotary glass holder with a pair of bifocal blanks thereon as in Fi Ida, 'XIV'anii XVII.

r Fig. II is a plan view of a single piece of glass, forming a blank for a pear of bifocal lenses, 80f substantially the same shape as the pairs of .lensblanks shown in Figs. I,- IVandVnw Fig. VIII is a plan view of a circular piece ,f glass adapted to. form a pair of bi ocal "rises, by the employment of the method I V Fig. IXlis divcrtical sectional view of the lap. glass, and glass holder arranged to abrade the major lns surfaces in accordance with Fig. V, and illustrating means for Fig. IX.

XI is a vertical sectional view of a simplified form of lap s indle bearing which Fig. IX.

Figs. XII, XIII'and XIV are diametrical sectional views of pairs of'lens blanks such as indicated in Figs. I, IV and V, illustrating successive steps in a method of surfacing the same. Fig. XII shows said blanks primarily surfaced to a .uniform curvature throughout the entirev areabf their upper to diopters. Fig. XIII further surfaced,' at the same curvature, so as 'to leave the minor areas projecting upwardly therefrom. Fig. shows said Fig. 11- is an elevation of the stop mechanism by which the movement of said lever and means illustrated in the preceding :fig-

supporting said lap in operative connection with the lever shown in Fig. I; said supportmay be substituted or that shown in h i a ma or lens surfaces 'whw sides; the curveindicated being minus six n shows sa1d' blanks with'theirmlnor areas in the same condition Fig. XXV for "as in Fig, XII but with their major areas Figs. XV, XVI and,XVII respectively show inner edge views of ective llndl.

vidual members of the pairs of lanks shown inFigs. vXII XIII and XIV. y

Fig. XVIII is a vertical mtional view similar to Fig. IX but showing the lap spina die bearing supported by. a detachable coupling connectingl it with the upper spindle of the machine s own in Fig. I; said spindle I beingri 'dly connected with the vertically adjustab e quill of said machine when thus used.

Fi XIX is an upper end vieivofthe lap spin le bearing and its pivot bar shown in, Fig. XVIII.

,Fi XX is a sectional view of the lap spin leshown in Fig. XVIII' showing the normalconstruction and position of the re silient ring carried by said spindle when the latteris withdrawnv from the hearing shown in Fig. XVIII.

Fig. XXI is a vertical sectional view 7 showing laps adapted to respectively abrade the ma]or and minor lenfs surfaces mounted upon a commonispindle upon which they maid be independently rotated at different sp s. 4

Fig. XXII isa fragments. sectional view of the lamps shown in Fig. XI, with their abrading surfaces covered by respective sheets of textile fabric secured by elastic I i lap havinggthe respectively difl'erently curved annular rading surfaces'for abrading the major and minor lens surfaces.-

Fig. XXIV is a plan view similar to Fig.-

VI but showing that the, contact between the lap and theglas arranged as in Fig. XXI is only at. a line, which is radial with respect to the lap axis, because both of the annular surfaces pfsaiddap' are respectively differently curved 'transeversely and circumferentially.

Fig. XXV is a vertical sectional view similar to Fig. XXIII but showing a lap aving an annular abradin surface for the is -'spherically curved i. e., arcually'curvedthe same both transversely and circumferentially, whereas,

the annular abrading surface for the minor lens surfaces is arcually curved respectively dilfierently transversely and circumferentia y.

' XXVIis a plan view similar to Fig.

X V but showing that whereasthe annulanab'rading surface of the lap shown in brading the minor lens surfaces presents only a line of contact to the glass,- which is radial with'respect to the lap axis; the annular abrading surface of said lap for the major lens surfaces presents an 189 .10 transverse section, of the surfacin mac in partlyshown in I and XX I is a fragmentary plan view of -a areaj -of'contact to the glass which is a lune of'a isphei-ical surface. i F XXVII is an elevation, partly in longitu inal section, of the surfacing machine rtly shown in Fig. I, looking toward the fi itintfllat' figure, but with-the upper and. lower-spindles in the positioncontemplated i|i"jFig.,.XVTIII' and showing the'lever supportxand its appurtenances as in Fig. IX.

XXVIII is an elevation, part1 in i machine which may be conveniently em-- ployed in roughing glass b1a'nks, by rotatmg them and alap upona common axis but respectively different 5 indles -which are- "relatively adjustable bot axially and laterr'emovably sup -;ally and, preferably, rotated in opposite (ii offi inding with the minimum centrifugal d! rect ons so as to attain; the maximum speed arge of the abradin material. In said machine, the lower spin e 8 is journaled in. the 'base frame land has the pulley 9 for rotation by the belt 10, and has the conical cap 11 for detachable engagement with the lass hoider 12 upon which the lens blanks 3 are detachably mounted, conveniently with pitch cement. .80

Said base 1 also sup- ;ports the table 15 upon which the pan 16 is orted in concentric relation with saidspin 1e 8. The upper spindle 18 t which is journ'aled in the frame '2, tilg ble V and capable of straight lateral movement on said base frame 1, is provided with the pulley 19 and belt 20 by which it may be ro- ,tated.' 'S'aid pulley 19 is keyed to said spindle 18 sothat the latter maybe raised and lowered through it by means of the quill 22 having rack teeth 23 engaging the gear 24 which may be turned by hand. Said quill may be prevented from rotating by a suit able key, adjustable by the set screw 32.

' Said spindle 18 has at its lower end the conical cap 29 for detachable engagement, directly, with ordinary spherical laps which may be rotated in axial alllWnu-nt with the spindle 8, and glass holdcrs 12 thereon, when the' set screw 32 in the quill is retracted. When said spindle 18 is prevented 'from rotating it may be used to support the other laps hereinafter described, for instance as shown in Fig. XVIII, to recisely deter mine the approach thereof to the glass. However, it is to be understood that other means may be-employed to efiect the grindingbfithe blanks preliminary to the employment ofthe laps which have their axes extending obliquely with respect to the axis 10f rotation-of the glass as herein set fbr'ih- Referring to Figs. I to III inclusivbfiit is to be understood that the universal fulcrumsupport and the stop-mechanism for the 16 Yet shown in Fig. I are mounted upon the table15' uponwhich ,the pan 16 rests. As

shownin Fig. II said fulcrufii 'hupport includes the socketbase 45 innwhich' the cy1indrical shank 46 of the yoke 47 may be turned and vertically adjusted and clamped by the set screw-48 when in adjusted position; said set screw 48 being in screw threaded en gement with said base 45. Safd yoke 4 has the oppositely alined cone pointed screws 50 engaiilg the sleeve 51in which the lever 52 may turned and longitudinally adjusted, and clamped "in adjusted position by theset screw 53 which is in screw 'thl'eaded enga ement with said sleeve. 3 However, it may observed that when said arts are adjusted and clamped by the screws 48 and 53, said lever 52 is free to oscillate in a vertical plane upon the common axis of said screws '50, and said lever is'conveniently provided with the handle 55 by which. it may be nanipulated as a support by which the-laps 56 and 57, indicate 1n dash lines in Figs. I, a

means above described, to such a degree that I find it convenient to provide stop mechanism at the handle end of said lever by which its moven'lent may be precisely limitcd. As indicated in Figs. I and III the stop bracket 60, which is conveniently mounted upon said table 15, carries the stop block 61 uponjthe bolt 62. which has a squared shank mounted, to slide in the slot 63 in said bracket and is rovided with the ring nut 64 by which sai block 61 maybe secured in any position oi adjustment to which it may be shifted by ;the thumb screws 65 and 66 which are in screw threaded en-' gagement with said bracl'et 60. 'Said lever is conveniently provided yvith'the stud 68 which may be selectively engaged with any link of the chain 69 at the upper end of the spring 70 whi is connected with said bracket 60, at its lower end, by the screw 71, and it is to be understood that the approach of the laps 56 and 57 to the glass, both laterally and 'veij'tically, is precisely'predetermined and limited by the location of said stop block 61. Forinstance, said lever t't resent lap in position to abrade the glass carried by the holder 12 and with aspace between the. lower side of said lever and the proximate up r surface of the recessed end of said bloc 61 corresponding \v-'th the thickness of the glass which is 0 a removed, and, said spring 70 i being connected with said lever 52 as above described, the abrading operation may pro-- ceed without further attention of the operator except as toithe maintenance of the proper quantity of abradin material and water. or other liquid vehic e between the pair of lap and the glass.

It is to be understood that although I have shown the glass upon the holders 12 in the form' of individual lens blanks 13, other I the holder 12, may be suitabl surfaced and I 15.

subsequently cut apart, on t e dotted dia metrical lineshown in Fig. VII, to form a pair of bifocal lenses. Moreover, a circular glass blank 74 such as shown in Fig; VIII may be thus surfaced and subsequently cut.

apart, upon any diametrical line, to form' a ifocal lenses. Said form 74 is advantageous in that defects due to accidental crumbling ofthe glass may be avoided in cutting the lenses, and said form 73 is advantageous in that only the minimum amount of glass is required for the same.

Fig. IX illustrates the lap 56, glass 13 I and glass holder 12 arranged to abrade the major lens surfaces in accordance with Figs. I and V; said lap being supported in operative connection with said'lev'er 52 by means capable of oscillatory adjustment in the plane of the radial line of contact of the lap. with the glass. Such means includes the coupling 76 which is longitudinally adjustable on said lever 52 and has the set screw 77 by which the pivot bar 7 8 may be rigidly clamped against the flattened Side of said lever in any position of adjustment; said bar,78 having its opposite sides flattened as shown in Fig. X. Said bar 78 is bifurcated at its lower end to receive the radial flange 80 of the spindle bearing casing 81, which is pivotally connected there with by the screw 82 which has a smooth cylindrical portion extending through said flange but is in screw threaded engagement with said bar 78, as indicated in dotted lines in Fig. X. It may be observed that the construction and arrangement of said screw 82 is such'that it may be slightly retraced to permit said flange to oscillate freely and be advanced to clamp saidflange between I the bifurcations of 'said bar 78. The oscilla- 55 tory movement of said flange 80 in said bar 78 is limited and the parts clamped in ad justed relation by the screw S-l-Ywhich ex tends freely through the openings 85 in said bar but is in threaded engagement with said flange S0. Said screw 84? may be jammed in adjusted position by the nut 87 shown in Fig. XIX.

Said lap spindle bearing casing 81, shown in Figs. IX and X. carries in its socket 88, a ball hearing which 13 conveniently con to ermit the la structed and arranged as shown in Fig. XVIII, including the outer shell 89 which .is tightly but detachablzefitted in said casing 81, so that it may I Said ball bearing placed when worn. in

removed and re-. j

eludes the sleeve- 90 through which the spin- 1 dle 91 of each lap to and from its operative position withou lateral lost motion. In operative position the upper cone point of the spindle of each lap 56 and 57 1s seated in the cone socket screw 92, which .is axially adjustable in screw threaded engagement in-,said casing 81 and is provided with the nut 93'bywhic it ma}, be secured in adjusted positliqn.

1 T' prevent accidental displaceme tof said a "r with theglass, by the lever 52, I find-it con venient to provide each'spindle 91 with. a.

latch spring 96 which is carried by the casing 81 an has one limb extending, in the slot- 56- and 57 may be slit 56 and 57- when raised'from contalct circumferential groove to receive tli'i.

97 in the-latter in registry with said groove,- I The construction and arrangement of 5 ch' resilient retaining means is such that it yi ds s to be manually shifted to an from operative position in said casing81.

It may e shown in Fig. IV, said lap 57 is so'set that the smaller circumferential edge of its abrading surface, which is indicated by thesmaller elliptical dash line is in contact with the glass 13, and is tangential toi the circular junction line between the major lens areas 98 and'the minor lens areas 99. Said junction line is indicated in Fig. IX'and in other sectional views of the glass, b short straight lines which extend vertica y downwardly from the upper surface of the glass,- but which are not intended toindicate any division in the glass, but merely toindicate'the positionof the'laps with reference'to said junction lines whlch are otherwise diflicult to locate in the sectional views in view of the slight diiference in curvature between the ad oining surfaces.- When the line of cooperation of the tool and glass coincides with the axis of rotation of the glass as indicated 'n Fig. IV, the abrading particles tend to travel tangentially to the circular junction same 1n approximately evolute paths, the directions of which vary somewhat with variations in the speed of travel ofsaid particles, which is the resultant of the rotation of both the glass and the abrading tooll When the line of coiiperation of the tool and glass is as indicated in Fig. I, the abrading particles travel across the circular junction line between the major and minor areas in paths which are either approximately evolute of involute in accordance with the direction (1 rotation of the abradin they travel involutely if said tool is rotated clockwise with reference to Fig. I, and evotool. a That is to's i observed that in theposition line between the lens areas and across the shown in' Fig. XVIII; whereby the glass is abraded by said lap in a direction transverse to said junction line, soas to sharply define the latter; the glass being rotated in the :direction of the arrow in Fig. IV while the same direction. Al-

lap is rotated in the be caused to rotate in though said lap may that direction merely that direction, I find it pre erable to rotate for rotating the lap at 101 engaging the groove 102 in th around the lap at a higher speed than the glassand this may be'conveniently done by the belt e.lap, as shown in Fig. .IX, and extending thence any suitable driving pulley. The reason successively with the lap l of the area of the glass which is to be abraded by the latter. The reason a higher'speed isto attain the maximum relative movement of the lap: and lasssurfaces which is possible with the chip oyment of a pulverulent abrad ing medium; such speed being limited by the centrifugal effect upon saidmaterial, for, if the lap is rotated at too great a speed said material will be thrown off the glass upon I which it must be retained to have any abradparticle of the lap.

The reason for rotating the lap ing effect. direction as the glass is to mimirregular particles of the abrading material which might beretained in damaging relation to the glass if the glass andlap are rotated in opposite directions,as the abrading material is then piled up by the opposite feeding movement thereof by the glass and It is to be noted that the abrasion is not effected by the surface of the lap but by the .pulvcrulent abrading material which is free to move between the adjacent surfaces of the lap and glass, and has a motion which is the resultant not only of the circular rotation of the lap and glass with their axes in the oblique relation described, but of the so called centrifugal force generated by such movement; the effect of said force being al- .ways to produce a tangential motion of each abrading material, outwardly with respect to the axis of rotation of the element supporting said particle at As the paths of said" by frictional engagement with the surface of the lass rotating in for rotating the glass, is, of course, to present at the l ne of contact a .any instant. That the glass is abraded in a comprehensive of the right angular relation as distinguished from the diagonal or oblique crossing movement contemplated,

which is the result of t; e traverse ofthe particles of the abradin material in evolute paths, under the severe forces acting upon them as aforesaid. Of course,

said paths of the abrading material are curvilinear, and

eccentric with reference to the axis of rotation of the glass as distinguished from the above contemplatedcirclesof rotation of the latter. Moreover, it is to be particularly noted that by the operation described, the

major and minor areas are abraded respec- -tively oppositely transversely to said junction line between. them.

Of course, saidlever 52, is set in respectively different positions in order toprcsent the annular 'abradin'g surfaces of said laps 56 and 5' Z ,re spectively in operative relation with the major and minor. lens surfaces of the glass 13. a. The dash line which is ,radial to the center of oscillationo'f said lever52 in FigiI indicates its position when supporting the lap 57, as in Fig. IV. The position of said lever shown in full lines in Fig. I is approximately that which it occupies when supporting said lap 56 as shown .in Figs. I, V and IX, it being thus shifted slightly more to the left, to bring the smaller circumferential line ofits annular abrading surface tangential to the circle defining the minor lens areas in Figs'I and V.

Fig. XI is a vertical sectional view of a spindleibearing casing 105 which is similar to said casing 81 but of simpler construction in that it has no hearing screw or not at the. upper end thereof; its cone socket 106 being adapted to receive the conical points of the lap spindles and'hold them'in concentric relation with said casing andthe ball bearing which isdetachably but tightly fitted in the socket 107 at the lower end thereof. 7 1

I find'it convenient to prepare the glass for abrasion by the conoidal laps 56 -and57 above described by primarily surfacing the blanks throughout the entire. area of their upper sides, for instance, as shown in Figs. XII and XV. Then, elther the minor areas may be further surfaced to the desired curvature, thus reducing them to a less thickness than the major areas, or the major areas may be further surfaced tothe proper curvaturc reducing them to less thickness than the minor areas, as shown in Figs. XIII and XVI. In either case, I prefer to effect such preliminary surfacing'with the axes:

ofrotation'ofthe laps eccentric to the axis ofrotationpf the lass, at the surface of the latter being ab ed, although radial with respect to the center of curvature of that surface, to make it impossible toroduce concentric scratches in the lass. or

instance, the dipper spherical su ace of the glass blanlgs 1 as shown in Fig. XII, has

"'8' center 'of curvature on a vertical line coincidentwith the unction line between said blanks and withthe axis of rotation of i that surface with the inner circular edge of its abrading surface in continuous con- I tact with said glass surface, but eccentric to scratches in the glass,

- curing it in adjusted; 29, so that said cou mg may the axis of rotation of the glass at said s herical surface of the latter bein abraded. owever, the axis of rotation o -sa1d lap f a will then be radial with res cct to said cen ter of curvature of that sur ace andilif both the his and the lap are rotated, t e glass will abraded and said spherical surface generated without gzducing concentric tric relation of the abrading tool and glass at'the surface of the latter bein Ine'ither-case, the glass may be nally surfaced as shown in Figs. VI, XIV and XVII v by the conoidal laps 56 and 57 above described, or laps of similar construction hereinafter described. V

It is to be understood that any of said la s may be provided with a cover of textile fabric or other-flexible sheet material 125 re- 'tained thereon by'the elastic sphincteral band-126 as shown in Fig. IX; such covering serving as vehicles toretain the pul-.

verulentabrading material upon-the abradin surfaces of the laps. i,

iig. XVIII is a :vertical sectional view similar to Fig. IX- but. showing the lap s indle bearing casing 128 supported by a etachable c0up'ling130 connecting it with the cap 29 of the upper spindle 18 of the machine shown in Fig. I; said spindle 18 being ri 'dly.connected with the vertically adjustab e quill 22 when thus used. Said couplin 130 has the set screw 131 for seition uggn said cap turned to present the axis 0 the 'lap spindle in a plane which is radial to the axis of rotation of the glass holder 12 or in tangentialrelation to a circle of rotation of the glass as above contemplated. Said coupling 136 also has the set screw 134 by which the ivot bar 135 may be rigidly held in ad uste position; 'said bar being constructed and arranged like'the'bar 78 above described, 5. e., it is bifurcated at its lower end to receive-the radial'fian e 136 of the sindle bearing casause of such eccen-.

abraded.

with by the screw 137 which has a smooth cylindrical portion extending through said flange 136 butis in screw threaded engage ment with said bar 135. The oscillatory movement ofsaid flange 136 in said bar 135 is limited and'the parts clamped in adjusted relation by the screw 139 which extends freely through the openings 140 in said baf' but is in threaded engagement with said flange 136, like said screw'84 above de scribed.

Said lap spindle bearingcasing' 128 icarries a ball bearingincluding an outer shell 89 tightly fitted in .said casing 128 and a sleeve rotatable in said caslng, and the has its spindle 143 provided withdiiferent means for preventin accidental axial displacement of the atter,- including ,the

lap 142, which is otherwise constructed-and arranged like the lap 57 above described,

resilient ring 5 which, as shown in Fig.

XX, is normally of slightly larger diameter than said spindle but is compressed to frictio'nally engage said sleeve 90, as shown in.

Fig. XVI I, whep said spindle is thrust through said sleeve 90 into the operative po-';

sition shown in said figure.

Although I find it convenient to employ the respectively independent laps b scribed so that the minor and major lens surfaces may be abraded, by different op erators at different times; it is to be linden stood that such conoidal laps may be 'employed to simultaneously abrade both the ma or and minor surfaces of the-same lass. For instance, as shown in Fig. XX the laps 146 and 147 which have annular abradingsurfaces respectively adapted to abrade the major lens surfaces 98 and minor lens surfaces 99 of the glass 13 which is rotated by the holder 12, shown in said figure, have x the common spindle 149 andmay be simultaneously rotated, uponthe same axis, by-' the belts 101, at respectively different speeds, i if desired, or they may both be rigidly con-- nected with said spindle by their respective set screws 1 51 and 152 so as to be rotated tother. The relative axial position of said aps 146 and 147 maybe precisely'predetermined by adjustment of the nuts 154 -which are in screw threaded engagement with the inner hub of said l ap'146. Such' construction and arrangement is advant'a- A geous in that the laps 146 and 147 may have their abl'ading surfaces separately ground to a variable extent and yet be precisely. ad-

justed for the desired cooperative effect upon the glass.

Whether rotated independently orclamped together, as above described; said la 5 146 and 147 are conveniently mounted or rotatitm in the spindle bearing pivot frame 156 having the adjustable bearing screws 157 and; 158 which may be set to hold said spindle 149, or the spindles of any. of the laps as; described. Said pivot frame 156 is conveniently h ounted for oscillation in the "yoke 15? which hasthe set screw- 160 for secun'ngiit in rigid relation with the cap 29.

of the spindle18 abovedescribed,and carries at the lower ends' of its bifurcations, opposite, axially'alined, screws 162 having conical heads 163 fitted in corre's sockets in said pivotframe'156 an having wing nutsz164, exterior tosaid'yoke 159 so that saidflirame 156'may be freed for ocillation in said. yoke or clamped in rigid relation therewithi I prefer to limit the oscillatory movement of said frame 156'in said yoke159 by providing the latter with the clamping' screw 167 having the conical head 168 extending in the arena! slot 169 in said frame 156; said screw 167 being provided with the wing nut 170 exterior to said yoke, byfwhich said frame 156 may be clamped in rigid relation withsaid yoke- Of course, if a, permanently rigid construction is desired, the bearing screws. 157 and 158 .may be directly mounted in the yoke 159, without the interposition of the frame 156.

As indicated in Fig-XXII, either or both aof said laps 146 and147 may haveits abradin%' surface provided with a cover of textile fa. ric retained thereon'by "an elasticsphincteral band 126.

As shown in Fig. XXIII, my improved surfacingmechanism may be further simplifiedby providing a single lap 173 having the respeetivel y differently curved annular abrading'surfaces 174 and 175, meeting at the circular line indicated at 176,and respectively adapted for abrading the major lens surfaces 98-and minor,v lens surfaces 99 of the glass '13 which is mounted to rotated on the holder 12 as above described. Said lap ,173 maybe mounted for rotation in any of" the lap spindle bearings above described but is shown mounted in the bearing 128' supported by the lever 52 with which it is adjustably connected by the coupling 76- above described.

Said lap .173 has annular abradingi; sur-- faces which are like those, of the laps 56, 57, 117, 121, 146 and 147 inthat they-are respectively differently curved transversely and circmnferentially'and. as indicated in Fig. XXI, the annular abrading surfaces 174 and 175 of said lap 173 are in contact with the glass only at a line 178 which 15 radial with respect to the lap axls.

As the laps above described'presiept only respective lines of contact to the ma or and minor lens surfaces, 'and the formerare of greaterareathan the latter, a longer time is required to produce a given surface upon 5 the n'iajorareas than upon the minor areas.

although the difference is minimized by the relatively greater diameter and consequent surface speed of movement of the annular onding or other-flexible sheet material 125 over the major glass areas 98 and abrading surfaeesof the la s which are applied to the major areas. 'l herefore, I find itconvenient to provide the lap 180 shownin Fig. XX", which differs from thela above described in that its annular-a rading surface 181 whichpis presented to the.

major glass surfaces 98 is spherically curved,-

2. e., arc'ually curved thesame' both trans: yersely and circumferentially;so'that, as. indicated in Fig. XXVI, said surfaces-181 I presents an area of contact to'the gl'ass which is a lune of a spherical surface, the

contour thereof, in plan, being'indicated by the dash lines 182 in F1 spherical abrading surface'of the lap '180 terminates at the circle indicated by-the dotted line 184in Fig. XXV, and the adjacent sented to the minor glass areas 99,='-is arou- .ally curved respectively difierentlytransversely and circumferentially so as to .pre-

annular abrading surface185, whiohis ref a sent only a line of contact to the glass-ask indicated at 187 in Fig. X-XY'I. Such construction of the abrading surface 185 necessitated by the fact that its curvature (four dioptric).is of greater radius transversely'than the curvature '(sixdio trio) of said abrading surface 181,,and, if sp disposed (as a zone ofa sphere'of" such greater radius) it would,'-of course, sweep eliminate the desired curvature of the latter.

erically It may be observed that in the employs: ment of both of the hips 173 and 180 thei smaller circumferential edges of the abrad, ing surfaces which are respectively in contact with the major and minor glass areas extend obliquely over the circular junction 1' line between said areas, from respectivelyopposite sides of said line; whereby the glass is abraded in adirection transverse to said junction line, so as to sharply define the latter. v

It is to be understood that said laps 173 and 180 may have their abrading surfaces covered with textile fabric or other flexible shcet'material 125 retain-fed thereon by'elas-fl tic sphincteral bands 126, as indicated in Fig. XXV. p,

It may be observed that the ball bearings above described have no means for compensating for wear which is incident to the rota:

tion of the laps at high speed, as they are, of an ordinary commercial type, and,

I through. the sleeves 90 of said bearings, toand from their operative position. Therefore, I have shown in Fig. XXV a lap spindle bearing casing 190 having tightly but in their respective diameters. Saidsleeve 192 has its conicalend 193 encircled by the double conical annular ball race ring 195 for the balls 196 which are embraced between said ring 195 and the nut 198 which is in screw threaded engagement with the upper end of said sleeve 192. Said nut 198 is a. complete annulus but has radial notches 199 which may be engaged by a screw driver or similar "implement inserted through the opening 200 in said bearing casing 190 to hold said nut 198 temporarily stationary while the sleeve 192 is being adjusted in engagement therewith. The construction and arrangement above described is such that when "said-nut -.l9 8 js temporarily prevented from rotating with the sleeve 192, and the latter is turned, either by a tool engaging the radial slots therein or by frictional engagement withthe lap spindle, said nut 198 is drawn toward the race ring 195 to take up all lost motion. Said screwthread connecting said sleeve 192 with said nut 198 is preferably so inclined as to be tightened by rota,-

-tion of said sleeve in the direction in which it is rotated With the lap spindle.

Although the supports for the lap spindle bearings above described as capable of oscillatory movement may be rigidly secured when adjusted to the proper angleto pro duce thedesired surface upon the glass, and the curvature of the glass surfaces abraded by the laps thus supported may be precisely predetermined by such adjustment and maintenance of the laps; it is to be noted that ordinarily lens surfacing operations are facilitated by permitting the laps to have such freedom of movement as to accommodate themselves'to the curvature of the glass, particularly during the polishing operation. Therefore, it may be observed that the bearings constructed'and arranged in accordance with my invention as above described, permit such freedom of movement, and laps embodying my invention may be thusused. For instance, glass which has been surfaced to the desired curvature by any convenient means and requires to be finally finished or polished may be subjected to the operation of the conoidal laps abo e described, with the latter free to oscillate to such extent as to accommodate themselves to the curvature determined by the glass ,I

00 itself, and, in such use of said laps their effect is rendered as accurate as possible by the fact that their centers of oscillation'are nearer the surface of the gla s being abraded than the center of curvature of the surface 66 whichkbeing formed; so as to stabilize the laps, with respect to the lass, regardless of their freedom' aforesaid. 1'. may be observed 1 that in Fig. XXI the center of oscillation of the laps is below the surface of the glass which being abraded,'-as distinguished 10' from the construction and arm ment 1 illustrated in the preceding figures, w erein the centers of oscillation of the respective laps are above the glass; however, in either case, the centers of oscillation are intermediate of the length of the lines of contact of the laps with the glass. Moreover itis-to be noted thatwhen permitted such freedom of oscillation, it is limited to planes which are radial with respect to the laps' and coin- 80. cident with the lines of contact which the laps present'to'the glass. q 1 I do not desire to limit myself-to the precise details of construction a'nd arran ment above described as it is obvious t .at various modifications may bejmade therein without departing from the essential features of my invention as definedinthe appended claims. i n I claim: y 7 1. The process of surfacing a bifocal lens, which consists in rotating a. lens blank while surfacing the major and minor areas thereof at different times; surfacing each of said areas by rotating an annular abrading element, on an axis obliquely transverse to the axis of rotation of said blank while" automatically axially movin said .abrading element toward said b and, predetermining the position of the surface when finished, upon each of said areas, by adjustably limiting the freedom of axial movement of the abradin element towardsaid blank; the fixis of sai abrading element being differently angularly adjusted with re- 10 spect to .the axis of sand blank in accordance with the area thereof being surfaced, and the freedom of axial movement of said abrading elementbeing differently limited in accordance with the area being surfaced; 11o" whereby the relative position of the surfaces of said two areas may 'be -prede-= termined. 2

2. The process of surfacing which consists in. rotating the article to be surfaced; contemporaneously rotating an abrading element on an axis obliquely transverse to the axis of rotation of said article, and in operative relation with said article in a plane.

"radial tothe axisgof said abrading element and tangential to a circle of rotation of saidarticle; automatically axiall moving said, abrading-elemcnt toward sai article as the surfacing operation proceeds; and predeterminin the position of the surface when finished, y ad ustablv limiting the freedom of axial movemento the abrading element toward said article. 3. The process of surfacing which consists in rotating the article to be surfaced;

contemporaneously rotatin an abrading element on an ax s oblique transverse to the axis of rotation of said article, and

in operative relation with said article in a plane radial-to the axis of said abradin element; automatically axiall' moving saic abrading element toward sai article as the surfacing operation proceeds; and predeterminin the position of the surface when finished,%y ad ustabl limiting the freedom of axial movement 0 toward said article.

4. The process of surfacing which consists in rotating the article to be surfaced; contemporaneoilsly rotatin an abrading ele ment on an axis oblique y transverse to the the abrading element axis of rotation of said article, and in operative relation with said article; automaticallyaxially moving said abrad1ng'element toward said article as the surfacing o oration proceeds; and predeterminin t e position of thesurface when finish by adjustably- ,limitin movement of the a rading element toward said article;

In testiniony whereof I have hereunto signed my naniie at Philadelphia Pennsyl- .vania,th1s twenty-sixth do, of lilay 1915. I ARTH E. PAIGE. Witnesse's; i FRANK'E. Pawn, ANNA ISRAELVITZ.

the freedom of axial 

